This invention generally relates to navigation or route guidance systems and, more particularly, to a map panning directional indicator for a navigation guidance system.
Navigation systems generally provide a recommended route from a starting point to a desired destination. Generally, the starting point and desired destination are selected from a large map database having a plurality of roads stored in a mass media storage, such as a CD ROM or hard drive, which includes the roads in the area to be travelled by the user. The navigation system can be located in a personal computer or it can be installed in a vehicle. If the navigation system is installed in a vehicle, the starting point is typically the current position of the vehicle, which can be input to the navigation system by an associated position determining system that usually includes a GPS (Global Positioning System) receiver.
The navigation system determines a route from the starting point to the destination utilizing an algorithm well-known to those in the art and currently in use in many navigation systems. Usually there are many potential routes between the selected starting point and the desired destination. Typical navigation systems select a recommended route based upon certain "cost" values associated with each segment of road in the map database. These cost values include the length of the road segment and the estimated time of travel through the road segment. The navigation system selects the potential route with the lowest total cost to be the recommended route. Depending upon the predetermined algorithm of the navigation system, the navigation system will recommend the route with the shortest total length, the lowest total time, or some weighted average of length and time.
The recommended route is then displayed to the user on a map showing the starting point and desired destination and highlighting the recommended route. Preferably, if the navigation system is installed in a vehicle, the navigation system displays the current position of the vehicle and provides turn-by-turn instructions to the driver, guiding the driver to the selected destination.
The size of a section of the map database that can be shown legibly is limited by the size of a display device of the navigation system. Frequently, a user wishes to see areas of the map database that are not currently displayed. Thus, the typical navigation system permits a user to pan or scroll to other areas of the map database and to display the panned map section. Many times the panned map section does not include the current vehicle location. The typical navigation system does not provide any indication to the user regarding either the relative distance between the current vehicle location and the panned map section or the direction of the current vehicle position relative to the panned map section.
Thus, it is desirable to provide a map panning directional indicator that continuously informs the user regarding both the distance between a panned map section and the current vehicle location and the direction of the current vehicle location relative to the panned map section.